Refactor: relocate dialer pkg

dialer/sockopt_linux.go

@@ -0,0 +1,44 @@
+package dialer
+
+import (
+	"net"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func setSocketOptions(network, address string, c syscall.RawConn, opts *Options) (err error) {
+	if opts == nil || !isTCPSocket(network) && !isUDPSocket(network) {
+		return
+	}
+
+	var innerErr error
+	err = c.Control(func(fd uintptr) {
+		host, _, _ := net.SplitHostPort(address)
+		if ip := net.ParseIP(host); ip != nil && !ip.IsGlobalUnicast() {
+			return
+		}
+
+		if opts.InterfaceName == "" && opts.InterfaceIndex != 0 {
+			if iface, err := net.InterfaceByIndex(opts.InterfaceIndex); err == nil {
+				opts.InterfaceName = iface.Name
+			}
+		}
+
+		if opts.InterfaceName != "" {
+			if innerErr = unix.BindToDevice(int(fd), opts.InterfaceName); innerErr != nil {
+				return
+			}
+		}
+		if opts.RoutingMark != 0 {
+			if innerErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, opts.RoutingMark); innerErr != nil {
+				return
+			}
+		}
+	})
+
+	if innerErr != nil {
+		err = innerErr
+	}
+	return
+}